Colorado Senate President John Morse unveiled the details of a new gun-control bill aimed squarely at those who own, sell or manufacture a class of weapons he says have “no public benefit” and “no business on our streets or in our forests”: military-style assault weapons.

The bill will hold gun sellers and manufacturers liable for damage caused by their weapons if they don’t conform to “the highest degree of care” in ensuring those weapons aren’t sold to future criminals. It makes owners of such weapons responsible for every shot fired outside the confines of a private residence.

“You fire this weapon, you own that bullet, whatever it does,” Morse said during a press conference announcing the details of the bill, which will be introduced in the state Senate on Wednesday.

The bill defines an “assault rifle” as any firearm other than a handgun, shotgun, bolt-action or lever-action rifle.

“These guns are four times as powerful as handguns,” he said. “That means they’re more effective at killing, they’re more efficient at killing, and they do a lot more collateral damage when they’re used.”

“There are people who believe they have the right to own these guns,” he continued, “but we need to be better at making sure that we’ve articulated clearly the responsibility that goes along with these guns.”

The bill exempts those who use an assault weapon to defend themselves or others inside a dwelling in response to a threat of physical force. Also excluded are police officers and military personnel acting within the scope of their duties.

Everyone else — from the shooter to the manufacturer — could be on the hook for civil damages.

If the bill were to become law, it would place new responsibilities on gun sellers to ensure they’re not selling assault weapons to potential criminals. It would be up to a jury to decide if a seller were negligent in selling a gun to someone he or she should have known would use it in a crime, Morse said.

“We set the standard that you’ve got to have reasonable grounds to know that this person is not going to use the gun dangerously or unlawfully,” he said.

Morse said that in the case of the Aurora theater shooting, had this law been in effect, those who sold suspect James Holmes his AR-15 would “risk getting sued because, by definition, you didn’t get the job accomplished.”

Pressed for an example of what would constitute a sale in which a gun store didn’t exercise “the highest degree of care,” Morse said selling “15 AR-15s” to a customer wearing a T-shirt that said “I love Osama bin Laden” would likely not meet the requirement if any of those guns were later used in a crime.

When asked if the bill could encourage political or racial profiling, he said only that sellers can “choose or not choose to sell their gun to anyone.”

He said the bill wasn’t meant as a de facto ban on assault rifles, but later said that he “would be OK” with the possibility that fewer gun store owners would take the risk of selling them.

The threshold for liability extended to manufacturers under the bill is even murkier, with Morse simply repeating that gun makers must exercise care to ship their weapons to retailers who display high standards for selling them to the public.

Morse said the bill wouldn’t violate the federal Commerce in Arms Act, which generally protects the gun industry from liability if their products are used in crimes. Such immunity, however, only applies to manufacturers and sellers who follow state law, as this bill will be if it passes.

Morse also said it would pass a Second Amendment test, citing a Supreme Court ruling that assault rifles are more susceptible to stringent regulations — including bans — than other firearms.

“The reality is, these folks don’t have a Second Amendment right to buy these guns,” he said. “I’m not going there with this bill. I’m granting them the right, if you will, as long as they take 100 percent responsibility, both to sell it, to buy it, to possess it, to shoot it, the whole kit and caboodle.

“You guys have to take this responsibility along with this so-called right.”